My Mom had ALS and I was her caregiver. She was often uncomfortable too. I used to have her lay on whatever side was comfy for her then pile a bunch of pillows behind her back so she would not fall back on her back. The problem with this is that she didn't have the strength to move the pillows when she became uncomfy, the solution to that was for her to bang on the wall with her cane as she had lost her ability to speak in July. (I know more info. than you needed!)

She often used to sleep sort of sitting up. I have one of those big cushions that have arms on them, they look like armchairs, I know you can get them at The Bay and Walmart here in Canada, we used to pile soft pillows on that so she could sleep or rest without lying flat on her back (she didn't like that at all as she would choke.)

I'm sorry I don't have a solution for your turning over in bed problem, I always helped my mom do this as she lost the use of her right arm.